272 THE DISSEMINATION OF OTHER DISEASES BY FLIES 



the fourteenth day after infection. In a further experiment flies 

 were fed upon tuberculous sputum and afterwards on non-tuber- 

 culous sputum. The tubercle bacilli were found in the intestinal 

 contents for at least four days, during which time the faeces were 

 also infected. These careful experiments confirm the conclusions 

 of the previous investigators as to the ability of flies to carry 

 B. tuberculosis in a virulent condition. 



Cholera. 



The necessity of guarding food against flies in the belief that 

 they might disseminate cholera was called attention to by Moore 

 in 1853, according to Nuttall and Jepson (1909). He stated that 

 " flies in the East have not far to pass from diseased evacuations 

 or from articles stained with such excreta, to food cooked and 

 uncooked." 



One of the first to suggest that flies may disseminate the 

 cholera spirillum was Nicholas (1873), who, in an interesting and 

 prophetic letter, said : " In 1849, on an occasion of going through 

 the wards of the Malta Hospital where a large amount of Asiatic 

 cholera was under treatment, my first impression of the possibility 

 of the transfer of the disease by flies was derived from the obser- 

 vation of the manner in which these voracious creatures, present 

 in great numbers, and having equal access to the dejections and 

 food of the patients, gorged themselves indiscriminately, and then 

 disgorged themselves on the food and drinking utensils. In 1850 

 the Superb, in common with the rest of the Mediterranean 

 squadron, was at sea for nearly six months ; during the greater 

 part of the time she had cholera on board. On putting to sea the 

 flies were in great force, but after a time the flies gradually dis- 

 appeared and the epidemic slowly subsided. On going into Malta 

 harbour, but without communicating with the shore, the flies 

 returned in greater force, and the cholera also with increased 

 violence. After more cruising at sea the flies disappeared gradu- 

 ally, with the subsidence of the disease. In the years of 1854 and 

 1866 in this country the periods of occurrence and disappearance 

 of the epidemics were co-incident with the fly season." In 1886, 

 Flugge, according to Nuttall and Jepson (I.e.), observed that flies 



